Meghan, Duchess of Sussex and Catherine, Duchess of Cambridge attend day twelve of the Wimbledon Lawn Tennis Championships at All England Lawn Tennis and Croquet Club on July 14, 2018 in London, England. Clive Mason/Getty Images

The battle of the princesses, Meghan Markle vs. Kate Middleton, continues in the press with Markle's guest-edited September issue of British Vogue magazine.

While Middleton appeared on the cover in 2016 to promote pictures of herself at the National Portrait Gallery, Markle opted not to grace the cover—she felt it would seem "boastful." Instead, she selected 15 women she admired to feature on the front page of the iconic fashion magazine.

Markle's decision is receiving backlash online, with some accusing her of stroking the fires of the feud between the princesses in the press, while others question her decision not to include the queen as one of her favorite trailblazing women. Markle's supporters, however, see a double standard of the treatment of the two princesses covers.

Markle's Vogue cover features leaders and activists like Salma Hayek Pinault, New Zealand Prime Minister Jacina Ardern, Jane Fonda, Laverne Cox, Yara Shahidi and Greta Thunberg, to name a few. One of the boxes features a reflective mirror as a metaphor, meant to tell readers they too can be "Forces for Change," the theme of the issue.

"These last seven months have been a rewarding process, curating and collaborating with Edward Enninful, British Vogue's editor-in-chief, to take the year's most-read fashion issue and steer its focus to the values, causes and people making impact in the world today," Markle said about the issue. "Through this lens I hope you'll feel the strength of the collective in the diverse selection of women chosen for the cover as well as the team of support I called upon within the issue to help bring this to light."

"I hope readers feel as inspired as I do, by the forces for change they'll find within these pages," she concluded.

British Vogue editor-in-chief Edward Enninful also commented on Markle's decision not to appear on the cover, saying, "From the very beginning, we talked about the cover—whether she would be on it or not. In the end, she felt that it would be in some ways a 'boastful' thing to do for this particular project. She wanted, instead, to focus on the women she admires."

People's reactions on Twitter have been mixed, with many faulting the princess for not including the queen.

"Why didn't she put more British people on the cover. And isn't the Queen an inspirational figure?" one Twitter user wrote.

why didn't she put more British people on the cover. and isn't the Queen an inspirational figure? https://t.co/oTeKqjIGhQ

Echoing the same sentiment, another Twitter user said, "Why isn't HM The Queen included on the cover of September's Vogue, @RoyalFamily? Her Majesty is the perfect role model: like many of us she had no choice but to do the job she was given."

"#MeghanMarkle has finally hit Narcissism Platinum Level. I don't think it is actually possible to be more of a Narcissist than her. Congratulations Meg. If there was an Award for Global Lifetime Achievement in Narcissim - you'd OWN that award."

#MeghanMarkle has finally hit Narcissism Platinum Level. I donât think it is actually possible to be more of a Narcissist than her. Congratulations Meg. If there was an Award for Global Lifetime Achievement in Narcissim - youâd OWN that award ð¥

Back in 2016, Middleton was asked by British Vogue to appear in the 100th-anniversary edition of the magazine to help promote the exhibition "Vogue 100: A Century of Style" at the National Portrait Gallery, which included shots of herself. Middleton agreed to appear on the cover and in a 10-page spread in the magazine.